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NAME | SYNOPSIS | DESCRIPTION | RETURN VALUE | NOTES | HISTORY | SEE ALSO | COLOPHON |
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SD_BUS_PATH_ENCODE(3) sd_bus_path_encode SD_BUS_PATH_ENCODE(3)
sd_bus_path_encode, sd_bus_path_encode_many, sd_bus_path_decode,
sd_bus_path_decode_many - Convert an external identifier into an
object path and back
#include <systemd/sd-bus.h>
int sd_bus_path_encode(const char *prefix,
const char *external_id, char **ret_path);
int sd_bus_path_encode_many(char **out, const char *path_template,
...);
int sd_bus_path_decode(const char *path, const char *prefix,
char **ret_external_id);
int sd_bus_path_decode_many(const char *path,
const char *path_template, ...);
sd_bus_path_encode() and sd_bus_path_decode() convert external
identifier strings into object paths and back. These functions are
useful to map application-specific string identifiers of any kind
into bus object paths in a simple, reversible and safe way.
sd_bus_path_encode() takes a bus path prefix and an external
identifier string as arguments, plus a place to store the returned
bus path string. The bus path prefix must be a valid bus path,
starting with a slash "/", and not ending in one. The external
identifier string may be in any format, may be the empty string,
and has no restrictions on the charset — however, it must always
be NUL-terminated. The returned string will be the concatenation
of the bus path prefix plus an escaped version of the external
identifier string. This operation may be reversed with
sd_bus_path_decode(). It is recommended to only use external
identifiers that generally require little escaping to be turned
into valid bus path identifiers (for example, by sticking to a
7-bit ASCII character set), in order to ensure the resulting bus
path is still short and easily processed.
sd_bus_path_decode() reverses the operation of
sd_bus_path_encode() and thus regenerates an external identifier
string from a bus path. It takes a bus path and a prefix string,
plus a place to store the returned external identifier string. If
the bus path does not start with the specified prefix, 0 is
returned and the returned string is set to NULL. Otherwise, the
string following the prefix is unescaped and returned in the
external identifier string.
The escaping used will replace all characters which are invalid in
a bus object path by "_", followed by a hexadecimal value. As a
special case, the empty string will be replaced by a lone "_".
sd_bus_path_encode_many() works like its counterpart
sd_bus_path_encode(), but takes a path template as argument and
encodes multiple labels according to its embedded directives. For
each "%" character found in the template, the caller must provide
a string via varargs, which will be encoded and embedded at the
position of the "%" character. Any other character in the template
is copied verbatim into the encoded path.
sd_bus_path_decode_many() does the reverse of
sd_bus_path_encode_many(). It decodes the passed object path
according to the given path template. For each "%" character in
the template, the caller must provide an output storage ("char
**") via varargs. The decoded label will be stored there. Each "%"
character will only match the current label. It will never match
across labels. Furthermore, only a single directive is allowed per
label. If NULL is passed as output storage, the label is verified
but not returned to the caller.
On success, sd_bus_path_encode() returns positive or 0, and a
valid bus path in the return argument. On success,
sd_bus_path_decode() returns a positive value if the prefixed
matched, or 0 if it did not. If the prefix matched, the external
identifier is returned in the return parameter. If it did not
match, NULL is returned in the return parameter. On failure, a
negative errno-style error number is returned by either function.
The returned strings must be free(3)'d by the caller.
Functions described here are available as a shared library, which
can be compiled against and linked to with the
libsystemd pkg-config(1) file.
The code described here uses getenv(3), which is declared to be
not multi-thread-safe. This means that the code calling the
functions described here must not call setenv(3) from a parallel
thread. It is recommended to only do calls to setenv() from an
early phase of the program when no other threads have been
started.
sd_bus_path_encode() and sd_bus_path_decode() were added in
version 211.
sd_bus_path_encode_many() and sd_bus_path_decode_many() were added
in version 227.
systemd(1), sd-bus(3), free(3)
This page is part of the systemd (systemd system and service
manager) project. Information about the project can be found at
⟨http://www.freedesktop.org/wiki/Software/systemd⟩. If you have a
bug report for this manual page, see
⟨http://www.freedesktop.org/wiki/Software/systemd/#bugreports⟩.
This page was obtained from the project's upstream Git repository
⟨https://github.com/systemd/systemd.git⟩ on 2025-08-11. (At that
time, the date of the most recent commit that was found in the
repository was 2025-08-11.) If you discover any rendering
problems in this HTML version of the page, or you believe there is
a better or more up-to-date source for the page, or you have
corrections or improvements to the information in this COLOPHON
(which is not part of the original manual page), send a mail to
man-pages@man7.org
systemd 258~rc2 SD_BUS_PATH_ENCODE(3)
Pages that refer to this page: sd-bus(3), sd_bus_message_new_method_call(3), systemd.directives(7), systemd.index(7)
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HTML rendering created 2025-09-06 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. |
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